Journal article
Erosion of Holocene Fluvial Terraces along the Memuro River in Western Tokachi, Hokkaido, by the Typhoon 1610 Event
Technical Note of the National Research Institute for Earth Science and Disaster Prevention, Vol.431, pp.59-64
2019
Abstract
Unprecedented heavy rainfall in August 2016 by Typhoon 1610 (Lionrock) caused a large volume of sediment discharge and severe lateral erosion along many rivers in the western Tokachi Plain, eastern Hokkaido. To examine details of the severe lateral erosion, distribution of fluvial terraces and their development processes were investigated along the Memuro River. Results show that fluvial terraces have developed through the late Pleistocene and Holocene. Two higher surfaces for the Pleistocene terraces and three lower surfaces for the Holocene terraces are recognized. A typical sequence of sediment layers of the Holocene terraces is humus-rich surface soil on the top, that is underlain by a sand and gravel layer. Beneath of the sand and gravel layer, a buried humus layer and/or finer flood deposit layer with charcoal fragments are deposited, which have been dated to be approximately 600 - 3600 y BP. Holocene time-marker tephras are occasionally found in the surface soil, showing that Holocene terraces mostly formed before 200 y BP. Analysis of satellite images and topography data assisted by field observation indicate that the 2016 event laterally eroded the Holocene terraces greatly on both banks along the upper to middle reaches by debris flows and alternately on right and left banks along the middle to lower reaches by meandering sheet flow. As a result, flood plains widened several times. These data suggest that the Holocene terraces have formed from debris-flows and/or floods with recurrence intervals in the order of 102 years, and developed through the period of 103 years. The 2016 event can be therefore understood to be a significant geomorphic event in Holocene fluvial landform development, that has time-scale of 103 years, along the Memuro River.
Details
- Title
- Erosion of Holocene Fluvial Terraces along the Memuro River in Western Tokachi, Hokkaido, by the Typhoon 1610 Event
- Authors
- Takahisa Furuichi (Author) - Hokkaido University, JapanSatoshi Ishimaru (Author) - Geological Survey of Hokkaido, JapanYasuhiro Shiono (Author) - Japan Conservation Engineers of Hokkaido Co Ltd, Japan
- Publication details
- Technical Note of the National Research Institute for Earth Science and Disaster Prevention, Vol.431, pp.59-64
- Publisher
- National Research Institute for Earth Science and Disaster Resilience
- Date published
- 2019
- ISSN
- 0917-057X; 0917-057X
- Organisation Unit
- University of the Sunshine Coast, Queensland; Sustainability Research Cluster
- Language
- Japanese
- Record Identifier
- 99451412102621
- Output Type
- Journal article
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